1. Field of the Invention
The present invention relates to information recording apparatuses, and, more particularly, to an image/audio information recording/reproduction apparatus for recording an image signal and audio signals accompanying the former signal.
2. Description of the Related Art
Apparatuses which record an image signal and audio signals, such as a sound effect, voice and music, accompanying the former signal, on the same recording medium and allows reproduction of recorded information as needed, are popular for business use as well as home use. Those apparatuses may be classified into video tape recorders (VTRs) which use a tape-shaped recording medium, and video disk apparatuses using a disk-shaped one.
Typical VTRs are video cassette recorders (VCRs) using a magnetic cassette tape wherein electrical image and audio information signals are converted by a signal converting unit into magnetic analog or digital information signals, which are magnetically recorded onto a running tape by a magnetic head.
Typical video disk apparatuses are optical disk apparatuses which employ an optical data recording system using a laser beam. In the optical disk apparatuses, electrical image and audio information signals undergo analog-to-digital conversion, and the resultant digital signals are then subjected to optical conversion in a converting section of a laser head or the like to produce a laser beam, which is so modulated as to reflect the optical information signals. This laser beam is "written" on a rotating optical disk. Another type of disk recording apparatuses are also known which employ a "static capacitance data recording" system.
It should be noted that, for both VTRs and video disk apparatuses, information writing is based on the relative movement between the data writing unit an recording medium. In this sense, these prior art information recording apparatuses may be called "dynamic" information recording apparatuses.
For existing dynamic information recording apparatuses including the aforementioned VTRs and video disk apparatuses, there has been a strong demand for improvement of the quality of recorded and reproduced audio signals in order to meet the recent prominent enhancement of image quality. To fulfill higher audio quality, it is popular to employ a digital recording system for recording/reproducing audio signals. Actually, VTRs and video disk apparatuses according to the digital recording system have already been made into practice.
The conventional dynamic information recording/reproduction apparatuses are suffering their low dynamic reliability as well as complication of the circuit structure. The first shortcoming, low dynamic reliability, is originated mainly from deterioration of a disk-shaped recording medium or occurrence of defects thereon; with a defect present on a recording medium for "storing" information, high-quality reproduction signals cannot be expected even if high-quality digital audio signals are properly recorded on the recording medium. On the other hand, the second shortcoming or the complicated circuit structure is originated mainly from additional provision of an error correcting circuit and an error compensating circuit which serve to compensate for the aforementioned deterioration of signal reproduction at the time of executing the analog-to-digital conversion. Building such additional circuitry in the apparatus undesirably increases the circuit scale of the apparatus, raises the manufacturing cost and hinders making the apparatus compact. Simplifying the additional circuitry, however, would certainly reduce the dynamic reliability.